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From: Quentin Perret <quentin.perret@arm.com>
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: Chandra Sekhar Lingutla <clingutla@codeaurora.org>,
	catalin.marinas@arm.com, will.deacon@arm.com,
	Jeremy Linton <jeremy.linton@arm.com>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	dietmar.eggemann@arm.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arch_topology: Update user supplied capacity to possible cpus in cluster
Date: Tue, 5 Mar 2019 09:23:25 +0000	[thread overview]
Message-ID: <20190305092322.q7odi3inofnvzhre@queper01-lin> (raw)
In-Reply-To: <20190304182138.GA7553@e107155-lin>

On Monday 04 Mar 2019 at 18:21:38 (+0000), Sudeep Holla wrote:
> On Sat, Mar 02, 2019 at 07:00:43PM +0530, Chandra Sekhar Lingutla wrote:
> > So cpus in cpu_topology->core_sibling mask would not need to have same
> > capacity_cpu ?
> 
> Yes, it need not. DSU is simple example. Even normal heterogeneous
> multi-cluster single socket systems will have all the cpus in the die
> present in core_siblings.
> 
> > Then i think, we should update the cpu_capacity for only requested cpu
> > right?
> 
> One possible solution and a simpler one. But I am open to any better
> alternative if it exists/possible.

How about we update the capacity for the related_cpus of the CPUFreq
policy ? This is what we're interested in here, I think, and is
orthogonal to the topology stuff. And that should map fairly well to the
core_sibling_mask for legacy platforms.

FWIW, we already mandate something similar for EAS for example
(see [1]), and I'm not sure we want to support having different uarchs
in the same freq domain here either, even though strictly speaking
DynamIQ doesn't forbid it.

[1] https://elixir.bootlin.com/linux/latest/source/kernel/power/energy_model.c#L170

[...]

> I was always under the impression that this was in debugfs and will be
> removed. I did mention this in one of the thread couple of months back.
> I was wrong and do understand the need for this on system where firmware
> doesn't provide this capacity value.
> 
> If possible I want to drop the write capability for the sysfs.

But yes, that is even better, if at all possible.

Thanks,
Quentin

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  reply	other threads:[~2019-03-05  9:23 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-28 11:53 [PATCH] arch_topology: Update user supplied capacity to possible cpus in cluster Lingutla Chandrasekhar
2019-02-28 12:19 ` Sudeep Holla
2019-02-28 14:38   ` Chandra Sekhar Lingutla
2019-02-28 15:25     ` Sudeep Holla
2019-03-02 13:30       ` Chandra Sekhar Lingutla
2019-03-04 18:21         ` Sudeep Holla
2019-03-05  9:23           ` Quentin Perret [this message]
2019-03-05 11:13             ` Sudeep Holla
2019-03-05 11:29               ` Quentin Perret
2019-03-05 11:36                 ` Sudeep Holla
2019-03-05 15:53                   ` Chandra Sekhar Lingutla
2019-03-05 16:12                     ` Quentin Perret
2019-03-05 16:54                     ` Sudeep Holla
2019-03-06 15:22                       ` Morten Rasmussen
2019-03-06 15:27                         ` [PATCH v1] arch_topology: Make cpu_capacity sysfs node as ready-only Lingutla Chandrasekhar
2019-03-06 15:27                           ` Lingutla Chandrasekhar
2019-03-07  7:28                           ` Juri Lelli
2019-03-07  7:28                             ` Juri Lelli
2019-03-07  9:31                             ` Quentin Perret
2019-03-07  9:31                               ` Quentin Perret
2019-03-07  9:57                               ` Juri Lelli
2019-03-07  9:57                                 ` Juri Lelli
2019-03-07 12:14                                 ` Quentin Perret
2019-03-07 12:14                                   ` Quentin Perret
2019-03-07 15:04                                   ` Sudeep Holla
2019-03-07 15:04                                     ` Sudeep Holla
2019-03-07 15:19                           ` Sudeep Holla
2019-03-07 15:19                             ` Sudeep Holla
2019-03-08 11:45                           ` Dietmar Eggemann
2019-03-08 11:45                             ` Dietmar Eggemann
2019-03-08 12:38                             ` [PATCH v2] " Lingutla Chandrasekhar
2019-03-08 12:38                               ` Lingutla Chandrasekhar
2019-03-27 10:56                               ` Quentin Perret
2019-03-27 10:56                                 ` Quentin Perret
2019-03-06  9:48                 ` [PATCH] arch_topology: Update user supplied capacity to possible cpus in cluster Dietmar Eggemann

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